Women who are obese at breast cancer diagnosis have a 1.5 to 2.5 increased risk of recurrence and death compared to their normal weight counterparts. Moreover, weight gain and decreased physical activity are common after diagnosis and also increase the likelihood of breast cancer recurrence and death. Rural women suffer from health disparities in breast cancer diagnosis and treatment. Women of the most rural counties also have the highest prevalence of obesity compared to urban women. To address these disparities, the overarching objective of this application is to develop a clinically effective and cost efficient strategy for delivering a weight control intervention to rural breast cancer survivors. Group phone-based treatment via conference call is a novel treatment delivery approach that we have shown to be effective for initial weight loss among rural breast cancer survivors and more effective than the standard individual phone-based approach among rural women. This innovative method of providing group treatment addresses access barriers in rural areas and may be especially ideal for rural breast cancer survivors because it provides social support in conjunction with a level of anonymity. Rural breast cancer survivors are more likely to be isolated, to have heightened concerns about privacy, and to report difficulty adjusting to breast cancer. At the same time, they have less access to professional support services, and thus are more likely to have unmet support needs surrounding both cancer and weight management. The opportunity to engage in lifestyle change with other survivors by phone may provide social support in a confidential setting at the same time it enhances diet, physical activity, and weight, as well as quality of life. However, the impact of group phone counseling during extended care for weight loss maintenance beyond six months remains unknown. Weight loss maintenance is the more challenging phase of treatment when weight regain is common, and this regain presents a potential risk for breast cancer recurrence. This randomized controlled trial will evaluate the effects of group phone-based treatment for weight loss maintenance among rural breast cancer survivors, compared to an established mail- based education comparison condition, subsequent to a six month group phone-based weight loss phase for both conditions. In addition to the intervention impact on weight loss maintenance, the study will provide estimates of incremental cost-effectiveness per kg loss between the two conditions and the impact on secondary outcomes including quality of life, breast cancer risk biomarkers, dietary intake, and physical activity. We aim to produce long-term weight loss maintenance, associated biomarker modulation, and improved quality of life in a cost-effective way that can be extended to hard-to-reach rural survivors.